Fiber-optics and optoelectronics are important aspects of modern networks, at least in part since they allow for more efficient, accurate and rapid transmission of data between various components in a network than many other types of non-optical counterparts. An optoelectronic transceiver module (“transceivers”) is an example of a device used in a communications network, and may be generically referred to as a “network device.” In general, these optical network devices communicate information in optical signal form back and forth to each other over optical fiber lines. At least one advantage of optical signals compared with electrical signals is the fact that there are a number of different ways, such as wavelength division multiplexing and time division multiplexing, to multiplex a group of optical data signals together. Because each individual optical data signal corresponds to a particular data channel, a multiplexed optical signal that includes several optical data signals multiplexed together is generally able to carry a much greater density of data than traditional electrical data signal counterparts.
Generally, networks can employ any number of ways to transmit multiplexed signals over optical fiber. In the most generic sense, a transmitting end comprises a plurality of optical transmitters installed at a corresponding plurality of different data ports. Each transmitter in the plurality of transmitters receives a respective electrical data signal, such as from some computerized device, and then converts the electrical data signal into a corresponding optical signal designated for a particular data port. A multiplexing component then takes each of the different data optical data signals from each data port and combines the optical data signals into a multiplexed optical data signal. The multiplexed optical data signal is then sent along an optical trunk line to a receiving end.
On the receiving end, a demultiplexer extracts each of the different optical data signals from the multiplexed optical data signal, by wavelength for example, and passes the extracted optical data signals to respective data ports. A given optical receiver positioned at each data port then converts the received optical data signal into a corresponding electrical data signal, which then can be passed onward to a computer system.
Although there are advantages to multiplexing optical data signals, multiplexing can give rise to some concerns regarding network metrics. For example, complicated network eavesdropping mechanisms may be required to measure traffic of each given channel. More particularly, conventional mechanisms for monitoring traffic involve installing additional demultiplexer and multiplexer components along a trunk line. A network administrator monitoring traffic can then adjust the multiplexer/demultiplexer component to monitor traffic of a particular optical channel. Unfortunately, multiplexer/demultiplexer components can be very expensive, and it can be time-consuming and expensive to break and reroute communication links when installing such multiplexer/demultiplexer components. As well, tuning from one wavelength to another, using the aforementioned systems and devices, may not occur rapidly enough to ensure that the traffic of one or more particular channels can be monitored as and when desired.
A further concern with arrangements such as those described above is that a dedicated wavelength filter, and associated processing components such as amplifiers, are required for each different wavelength of the multiplexed optical data signal that is to be analyzed. Correspondingly, some arrangements additionally require that an individual fiber, for each wavelength of the multiplexed signal, be connected to the trunk line that carries the multiplexed optical data signal. Such a multiplicity of components, connections and systems results in a relatively high cost, complexity, and maintenance burden associated with such systems.
Other conventional mechanisms for monitoring network traffic can include the use of a monitoring “tap” installed at each given port after or before an optical data signal associated with that port has been multiplexed or extracted. For example, a network administrator might use a fabric layer switch at each given port, and then rove from one port to the next to monitor network traffic at each port. Again however, the costs and time associated with installing a tap at each port can be resource intensive and the resulting system may be difficult to manage, particularly where large numbers of ports are involved.
Yet other mechanisms for monitoring network traffic can involve monitoring different data channels using inter-switch link (ISL) techniques. With ISL techniques, a filter on the trunk line monitors a particular data channel by reading those data packets that correspond to a particular data channel assignment. Where ISL techniques are employed however, data packets from the same conversation can be sent over different switching routes with the result that identification of the beginning and end of a specific conversation can be quite difficult. More particularly, monitoring software typically requires knowledge of the originating and ending ports in order to be able to determine whether any data packets associated with a given conversation have been lost and thus require retransmission. Thus, the very nature of such an ISL network can make data monitoring of specific conversations, much less gathering all data packets from the same conversation, difficult if not impossible, particularly for networks running at relatively high data rates, such as speeds of 10 Gb/s or higher.
Accordingly, there are a number of problems encountered when trying to selectively monitor one, some, or all data channels on an optical network, and in a manner that is both resource and cost-effective.